JP2023023026A - paper tray container - Google Patents

Abstract

To obtain a paper container that can be heated in a microwave oven and can be held by hand without getting burned even when the contents are heated.SOLUTION: A paper tray container (1) of the present invention is formed from a laminated sheet (10) which is fabricated by stacking at least the following layers from the top surface: a barrier film layer (101) comprising a barrier layer; a paper base material layer (102); and a foaming agent-containing low melting point thermoplastic resin layer (103), wherein the paper base material layer has a basis weight in the range of 80 g/m2 or more and 400 g/m2 or less, and whose breaking strength in the machine direction (MD direction) is 50 to 500 N/15 mm and the breaking strength in the width direction (TD direction) is 30 to 400 N/15 mm; wherein the foaming agent-containing low melting point thermoplastic resin layer has a resin melting point of 130°C or less, and the foaming agent is a type of microcapsule made from thermoplastic resin whose diameter is 5 to 50 μm, whose shell thickness is 2 to 15 μm, and whose inclusion is a hydrocarbon; and wherein the above laminated sheet is heat-foamed and molded to form the container having a flange portion.SELECTED DRAWING: Figure 3

Description

TECHNICAL FIELD The present invention relates to a tray container which is made of a base material containing paper, which can be heated in a microwave oven, which has heat insulating properties so that it can be held by hand after heating, and which is lightweight and easy to dispose of.

Conventionally, plastic containers have been used as food storage containers or packaging materials for storing various industrial products. However, in recent years, in view of environmental problems, etc., paper containers are being adopted. However, some types of paper cannot be easily molded, so there has been a demand for easy-to-process paper materials and containers using them.

For example, in Patent Document 1, as claim 1,
Satisfy the following four conditions (1) to (4),
It has a high density layer with a basis weight of 15 to 100 g/m ² and a density of 0.7 to 0.9 g/cm ³ and a low density layer with a density of 0.3 to 0.6 g/cm ³ and a basis weight of 100 to 500 g/m ² , a total density of 0.4 to 0.7 g/cm ³ , and a low-density layer mainly composed of pulp selected from at least one of mechanical pulp, curled fiber, and mercerized pulp A base paper for draw forming, which is obtained by making a base paper for forming using a multi-layer former.
(1) Tensile strength (JIS-P8113) of 2.0 kN/m or more.
(2) Elongation at break (JIS-P8113) of 1.5% or more.
(3) The critical compressive stress defined by the following formula is in the range of 1 to 10 MPa.
Critical compressive stress = A/B
However, A indicates the compressive strength according to JIS-P8126, and B indicates the loaded partial area of the test piece when the compressive strength was measured.
(4) The amount of compressive deformation when a compressive stress of 20 kgf/cm ² is applied in the thickness direction is proposed to be 10% or more.
Further, in claim 2, the base paper for drawing processing according to claim 1 is drawn using a press mold at a temperature of 100 to 150° C. and a press pressure of 10 to 100 kgf/cm ² . We are proposing a paper molded container that

Paper-made containers made from such base paper for draw-forming processing are too hot to hold with bare hands when cooked in a microwave oven. , there were problems such as getting burned.

Japanese Patent No. 4039006

Accordingly, it is an object of the present invention to provide a paper container that can be heated in a microwave oven and that can be held by hand without being burned even when the contents are heated.

The present invention
Formed from a laminated sheet having, from the top, at least, a barrier film layer including a barrier layer, a paper base layer, and a low melting point thermoplastic resin layer containing a foaming agent,
The paper base layer has a basis weight in the range of 80 g/m ² or more and 400 g/m ² or less, and a breaking strength of 50 to 500 N/15 mm in the machine direction (MD direction) and in the width direction (TD direction). 30 to 400N/15mm,
The foaming agent-containing low melting point thermoplastic resin layer includes a thermoplastic polymer having a resin melting point of 130° C. or less, a foaming agent having a diameter of 5 to 50 μm, and a shell thickness of 2 to 15 μm. is a hydrocarbon, in the form of microcapsules,
A paper tray container is characterized in that the laminated sheet is used as a base material, and the container is heat-molded and foamed with the foaming agent to form a container having a flange.

The paper tray container of the present invention has a low-melting thermoplastic resin layer containing a foaming agent together with a paper base layer, which foams to improve heat insulation. The surface of the tray container does not easily become hot and can be held by hand without getting burned.

1 is a plan view of a paper tray container main body in the first embodiment of the present invention; FIG. 1 is a longitudinal sectional view of a paper tray container main body in a first embodiment of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a paper tray container in a first embodiment and a second embodiment of the present invention; FIG. 3 is a schematic diagram showing a configuration example of a laminated sheet used for the paper tray container body of the present invention.

Hereinafter, the paper tray container body of the present invention will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a schematic plan view of a paper tray container body 1 according to this embodiment. FIG. 2 is a cross-sectional view taken along line II-II of FIG. A paper tray container body 1 shown in FIGS. 1 and 2 is a molded product for accommodating various contents. The main component of the paper tray container body 1 is paper.

The paper tray container body 1 can have required performance (for example, gas barrier properties, light shielding properties, water resistance, temperature and humidity resistance, mechanical strength, ease of printing, suitability for printing, ease of decoration, etc.). Gas barrier property means the ability to prevent or suppress permeation of gases such as oxygen and water vapor. Water resistance is evaluated by the rate of decrease in strength when the paper container is wet. The printability is evaluated by the number of pinholes, wormholes, etc. in the printed portion. For example, the higher the printability, the smaller the number of pinholes and the like in the printed portion, so that the portion tends to be more color-developing.

The paper tray container body 1 has a bottom portion 2, a side wall portion 3 erected from the bottom portion 2, and a flange portion 4 extending from a tip 3a of the side wall portion 3, and an opening defined by the tip 3a. An edge OE is provided. The paper tray container body 1 is formed by molding a laminated sheet 10 (see FIG. 4) having a paper substrate 102 by, for example, at least one of press molding, vacuum molding, air pressure molding, and vacuum air pressure molding. obtained by Therefore, the bottom portion 2, the side wall portion 3, and the flange portion 4 are portions where the laminated sheet 10 is deformed. In other words, the bottom portion 2 , side wall portion 3 and flange portion 4 are formed from one laminated sheet 10 .
In this embodiment, the paper tray container body 1 is molded by press molding. The bottom portion 2, the side wall portion 3, and the flange portion 4 may be formed at the same time or may be formed at different timings.

Directions X, Y, Z orthogonal to each other are shown in FIGS. 1 and 2 . Each of the directions X and Y corresponds to one direction in the horizontal direction, and the direction Z corresponds to the vertical direction orthogonal to the horizontal direction. Below, the structures of the bottom portion 2, side wall portion 3, and flange portion 4 of the paper tray container body 1 will be described using the directions X, Y, and Z (or the horizontal direction).

The bottom portion 2 is a portion on which the contents contained in the paper tray container body 1 are placed. The bottom portion 2 is a plate-like portion extending in the horizontal direction, and has a substantially rectangular shape with rounded corners when viewed from the direction Z. As shown in FIG. Of the four sides of the bottom portion 2, two sides along the direction X correspond to long sides, and two sides along the direction Y correspond to short sides. Although the entire bottom portion 2 extends in the horizontal direction in this embodiment, it is not limited to this. For example, a part of the bottom portion 2 may be formed with a concave portion, a convex portion, or the like. The contact area between the bottom portion 2 and the contents can be reduced by forming the concave portion, the convex portion, and the like on the bottom portion 2 . Herein, if the bottom part 2 extends horizontally when viewed from the direction Z, it can be considered as horizontally extending.

The side wall portion 3 is a portion that regulates the movement of the contents accommodated in the paper tray container body 1 along the directions X and Y. As shown in FIG. The side wall portion 3 extends outward from the edge of the bottom portion 2 when viewed in the direction Z, and surrounds the bottom portion 2 . A tip 3a of the side wall portion 3 is a portion connected to the flange portion 4, and has a substantially rectangular shape with rounded corners when viewed from the direction Z. As shown in FIG. The dimension S1 of the tip 3a along the direction X corresponds to the dimension of the long side of the open end OE, and the dimension S2 of the tip 3a along the direction Y corresponds to the dimension of the short side of the open end OE. Each of the dimensions S1 and S2 is, for example, 30 mm or more and 350 mm or less. In this case, damage during formation of the paper tray container main body 1 can be suppressed, and the paper tray container main body 1 having a sufficient depth can be formed. In this embodiment, the maximum length L of the open end OE corresponds to the diagonal line of the figure drawn by the tip 3a. The maximum length L is, for example, 42 mm or more and 495 mm or less.

The depth of the paper tray container body 1 corresponds to the distance H between the bottom portion 2 and the tip 3a of the side wall portion 3 along the Z direction. A ratio of the distance H to the maximum length L of the open end OE is, for example, 2.0% or more and 25.0% or less. In this case, damage during formation of the paper tray container main body 1 can be suppressed, and the paper tray container main body 1 having a sufficient depth can be formed. The lower limit of the above ratio may be 2.7% to 5.0%. The upper limit of the ratio may be 8.0% to 20.0%.

A ratio of the distance H to the dimension S1 is, for example, 5.0% or more and 25.0% or less. The lower limit of the ratio may be 5.4% to 9.0%. The upper limit of the ratio may be 22.5% or 20.0%.

The side wall portion 3 has a trunk portion 11 positioned between the bottom portion 2 and the flange portion 4 and a waist portion 12 connecting the bottom portion 2 and the trunk portion 11 . The trunk portion 11 is a portion that extends so as to be inclined with respect to the bottom portion 2 . A concave portion, a convex portion, or the like may be formed in a part of the body portion 11 . An angle θ formed between the trunk portion 11 and the virtual plane VP extending in the directions X and Y at the tip 3a of the side wall portion 3 is, for example, 15° or more and 65° or less. When the angle θ is 15° or more, the paper container 1 having a sufficient depth can be formed. When the angle θ is 65° or less, damage during formation of the paper container 1 can be suppressed. The lower limit of the angle θ is preferably 20° to 30°, and the upper limit of the angle θ is preferably 35° to 60°.

The waist portion 12 is a connecting portion to the bottom portion 2 and the trunk portion 11 and is a curved portion of the side wall portion 3 . The waist portion 12 is provided on the opposite side of the side wall portion 3 from the tip 3a. A curvature radius R of the waist portion 12 is, for example, 8 mm or more and 30 mm or less. When the radius of curvature R is 8 mm or more, damage during formation of the paper container 1 can be suppressed. By setting the curvature radius R to 30 mm or less, the paper container 1 having a sufficient depth can be formed. The lower limit of the radius of curvature R is preferably 10 mm, and the upper limit is preferably 25 mm.

The flange portion 4 is an edge portion of the paper tray container main body 1 and has a substantially rectangular frame shape with rounded corners when viewed from the direction Z. As shown in FIG. For example, when the paper tray container body 1 is sealed with the lid member 5, the flange portion 4 can function as a portion to which the lid member 5 is attached.
In this case, the lid member 5 may be welded to the flange portion 4 as in the first embodiment shown in FIG. 3-1. Alternatively, the flange portion 4 and the lid member 5 may be adhered via an adhesive.
The flange portion 4 is smooth when viewed in the Z direction. In other words, the surface 4a of the flange portion 4 when viewed from the direction Z is not formed with irregularities such as ruled lines. As a result, the flange portion 4 and the lid member 5 can be firmly adhered to each other. Therefore, the contents accommodated in the paper tray container main body 1 can be tightly sealed. The roughness of the surface 4a of the flange portion 4 is preferably 20 μm or more and 500 μm or less in arithmetic mean roughness defined by JIS B 0601:2013, for example.

Although the flange portion 4 extends along the directions X and Y in the first embodiment, it is not limited to this. The flange portion 4 may be inclined with respect to the virtual plane VP. The width of the flange portion 4 is, for example, 2 mm or more and 40 mm or less. In this case, the contact area with respect to the packaging sheet or the like can be ensured.

FIG. 3-2 shows an example of a second embodiment in which two paper tray container bodies 1 face each other at the flange portions 4 and the flange portions 4 are fused to each other.
In this way, the deep paper tray container main bodies 1 can face each other to form a container capable of accommodating thick contents without using a cover material.

Next, an example of the laminated sheet 20 as a material for the paper tray container body 1 will be described with reference to FIG.
FIG. 4-1 is a schematic cross-sectional view of a first structural example of a laminated sheet. As shown in FIG. 4-1, the laminated sheet 20 of the first structural example includes, from the top, a barrier film layer 101 including a barrier layer, a paper base 102 as a base laminated on the barrier film layer, a paper It is formed from a laminated sheet 10 having a foaming agent-containing low melting point resin layer 103 laminated on a base material layer.

The paper base material 102 is a sheet-like member formed from paper itself.
Paper constituting the paper base layer 102 of the base material is, for example, woodfree paper, special woodfree paper, coated paper, art paper, cast coated paper, Japanese paper, imitation paper, kraft paper, and the like. From the standpoint of the appearance of the outer surface of the paper tray container body 1, the base material used for the paper base layer 102 may be unryu paper or mixed paper.

The basis weight of the paper base material layer 102 of the base material is 80 g/m ² or more and 300 g/m ² or less.
With a basis weight of 80 g/m ² or more, the physical strength of the paper tray container main body 1 can be ensured. If the basis weight is 400 g/m ² or more, problems arise such as the base material not stretching along the shape of the mold and the base material becoming expensive. Therefore, by setting the weight to 80 g/m ² or more and the basis weight to 400 g/m ² or less, the paper tray container body 1 can be stably manufactured at low cost by press molding or the like.

Furthermore, the breaking strength of the paper substrate 102 in the MD (Machine-Direction) is 50 N/15 mm or more and 500 N/15 mm or less. Moreover, the breaking strength of the paper substrate 102 in the TD direction is set to 30 N/15 mm or more and 400 N/15 mm or less.
The paper base material 102 having the breaking strength within these ranges can satisfactorily form the paper tray container body 1 .
In other words, if the breaking strength of the paper base material 102 is less than 30 N/15 mm, there arises a problem that the base material breaks during molding. Further, when the breaking strength of the paper base material 102 is 400 N/15 mm or more, the base material is hard, and there arises a problem that the base material does not stretch along the shape of the mold.
The breaking strength of the paper substrate 102 is measured by the method specified in JIS P 8113:2006.

Moreover, the elongation at break of the paper base material 102 in the MD direction of the paper base material 102 is set to 1.5% or more and less than 20%. If the breaking elongation of the paper base material 102 in the MD direction is less than 1.5%, there arises a problem that even if pressed with a mold, it cannot be molded into a shape along the mold.
Further, if the elongation at break of the paper base material 102 is 20% or more, there arises a problem that the container becomes thin and cannot maintain its shape.
Therefore, by setting the elongation at break of the paper substrate 102 to 1.5% or more and less than 20%, the paper substrate can be molded well along the mold without breaking.
The breaking elongation of the paper substrate 102 in the MD direction corresponds to the tensile breaking elongation defined in JIS P 8113:2006. The MD direction corresponds to the fiber direction of paper, and can be specified by observing the cross section of the paper substrate 102, for example.

Further, the elongation at break of the paper base material 102 in the TD (Transverse-Direction) of the paper base material 102 is, for example, 0.5% or more and less than 20%. When the breaking elongation of the paper base material 102 in the TD direction is 1.5% or more, the paper tray container main body 1 can be molded well.
The breaking elongation of the paper base 102 in the TD direction of less than 20% facilitates the production of the paper base 102 . The breaking elongation of the paper substrate 102 in the TD direction corresponds to the tensile breaking elongation specified in JIS P 8113:2006. The TD direction corresponds to a direction orthogonal to the MD direction when viewed from the thickness direction of the paper substrate 102 .

The barrier film layer 101 including a barrier layer is a layer for improving the performance required of the paper tray container body 1, and coats part or all of the main surface 102b. When the paper tray container main body 1 is formed of the laminated sheet 10 , the barrier film layer 101 is positioned on the inner surface side of the paper tray container main body 1 . The barrier film layer 101 may have a single layer structure or a multilayer structure. When the barrier film layer 101 has a multilayer structure, each layer included in the barrier film layer 101 may be formed simultaneously by a co-extrusion method. The barrier film layer 101 may be a layer laminated on the principal surface 102b of the paper substrate 102, or may be a layer coating the principal surface 102b. The barrier film layer 101 exhibits, for example, water resistance, oil resistance, and the like. The thickness of the barrier film layer 101 is, for example, 50 μm or more and 200 μm or less.

The barrier film layer 101 is a layer containing at least one of, for example, a polyolefin film, a resin film, an inorganic coating layer, and the like.
A polyolefin film is a film made mainly of polyolefin such as polyethylene (PE) and polypropylene (PP). Polyolefin films are formed of, for example, low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), and the like.
The resin film is made of, for example, polyethylene terephthalate (PET), polyvinylidene chloride (PVDC), ethylene vinyl alcohol copolymer (EVOH), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), or the like. Resin films include polybutylene succinate (PBS), polylactic acid (PLA), polyhydroxyalkanoic acid (PHA), poly(butylene adipate/terephthalate) (PBAT), polycaprolactone (PCL), poly(hydroxybutyrate/hydroxy hexanoate) (PHBH) and other biodegradable resins.
The inorganic coating layer is formed by vapor-depositing metal such as aluminum, metal oxide such as alumina, silica, and silicon oxide on the substrate 21, for example.
When the barrier film layer 101 contains a polyolefin film and a resin film, the polyolefin film and the resin film may be co-extruded or molded at different timings.
In addition, "biodegradability" means that a polymer can be converted into an oligomer, a monomer, or a Or, it is the property of being decomposed to even lower-molecular-weight substances.

Various additives such as flame retardants, slip agents, antiblocking agents, antioxidants, and light stabilizers may be added to the barrier film layer 101 .

The low-melting-point resin layer 103 containing a foaming agent is a resin layer in which a foaming agent contained in microcapsules made of hydrocarbon processed into a shell with a diameter of 5 to 50 μm is dispersed inside the low-melting-point thermoplastic resin layer.

The foaming agent preferably has an expansion ratio of 5 times or more. The foaming starting temperature of the foaming agent is preferably 16° C. or higher, preferably 20° C. or higher, than the melting point of the low-melting thermoplastic resin. Specifically, azodicarbonamide (H ₂ NOCN=NCONH ₂ ), (foaming starting temperature: 140 to 209° C.) and the like can be used.
If the foaming ratio is less than 5 times, the heat insulating property is low, and when heated at a high temperature, it is hot and difficult to lift by hand. Also, if the foaming start temperature is lower than the melting point of the low-melting thermoplastic resin by 15°C, there is a problem that stable sealing performance cannot be obtained when sealing with the lid member, so the temperature is set to 16°C or higher.

The low-melting thermoplastic resin in which the foaming agent is dispersed is a resin having a melting point of 130° C. or lower, such as low-density polyethylene resin, linear low-density polyethylene resin, ethylene/vinyl acetate copolymer, ethylene/methacrylic acid. Copolymers, ethylene/acrylic acid copolymers, ethylene/ethyl acrylate copolymers, ionomer resins, and the like can be considered.
The amount of foaming agent to be added is 0.9 wt % or more and 5.1 wt % or less of the base low-melting thermoplastic resin. It is preferably 1 wt % or more and 5 wt % or less.
If the amount of the foaming agent added is less than 0.9 wt%, the thickness will not be very thick even if foaming occurs, and the surface temperature will be such that it is impossible to hold the paper tray container of the present invention heated to a high temperature by hand. a problem arises.
If the amount of foaming agent added is 5.1 wt% or more, uniform foaming cannot be achieved, and the resin that supports the layer cannot form a strong curtain and is easily broken. Therefore, the amount of foaming agent to be added is set to 0.9 wt % or more and 5.1 wt % or less.
Dry blending and melt blending can be used as methods for adding the blowing agent.

The layer thickness of the foaming agent-containing low melting point resin layer 103 is 30 μm or more and 200 μm or less, preferably 50 μm or more and 150 μm or less.
If the thickness is less than 30 μm, there is no effect of heat insulation, and the problem arises that the surface temperature of the paper tray container of the present invention, which has been heated to a high temperature, becomes unreasonable to hold by hand.
Moreover, if the thickness is 200 μm or more, there is a problem that the price becomes too high.

4-2 is a schematic cross-sectional view showing a second structural example of the laminated sheet 10. FIG.
The laminated sheet 10 shown in the second configuration example of FIG. The laminated sheet 10 has a foaming agent-containing low-melting resin layer 103 and a paper base material 104 laminated on the outer side of the foaming agent-containing low-melting resin layer 103 .
The basis weight of the paper base material of this second structural example is 100 to 400 g/m ² as the sum of the two layers.
The laminated sheet 10 of this second configuration example has high heat insulation by sandwiching the low-melting-point resin layer 103 containing a foaming agent between two paper substrates. You can get a container that is difficult to clean.

4-3 is a schematic cross-sectional view showing a third structural example of the laminated sheet 10. FIG.
The laminated sheet 10 shown in the third configuration example of FIG. It has a low-melting-point resin layer 103 containing an agent, a paper substrate 104 laminated on the outside of the low-melting-point resin layer 103 containing a foaming agent, and a low-melting-point resin layer 105 containing a foaming agent laminated on the outer paper substrate 104. It is formed from a laminated sheet 10 .
The basis weight of the paper base material layer of this third configuration example is also set to 100 to 400 g/m ² as the sum of the two layers.
The laminated sheet 10 of this third configuration example can be heated in the same way as the first configuration example and the second configuration example, but also has a higher heat insulating property, so when the container is taken out after heating, it is not hot and burns. It is a container that is hard to keep warm and can be kept warm for a long time.

FIG. 3 is a schematic diagram showing the paper tray container 1 according to this embodiment.
A first embodiment example of a packaging container 50 shown in FIG. 3-1 has a paper tray container 1 and a lid member 5 that seals an open end OE.
The lid member 5 seals the open end OE by being in close contact with the flange portion 4 . The lid member 5 is joined to the flange portion 4 of the paper container 1 by, for example, heat sealing, impulse sealing, ultrasonic sealing, or the like.
At this time, the lid member 5 may be adhered to the flange portion 4 via an adhesive or the like, or may be welded to the flange portion 4 .
The sheet forming the lid member 5 may be, for example, a plastic film. From the viewpoint of environmental protection, the plastic film may be formed from a biodegradable resin, and the laminated sheet used for the paper tray container body 1 may be used in an unmolded sheet form.

Second Embodiment of Packaging Container 50 Shown in FIG. As a result, the volume of the packaging container 30 can be easily increased as compared with the case where the paper container 1 is simply sealed with a film or the like.

Next, an example of a method for manufacturing the paper tray container main body according to this embodiment will be described.
First, a sheet having a paper substrate 102 is prepared (first step). In the first step, a laminate sheet 10 having a predetermined size and having a barrier film 101, a paper substrate 102, and a foaming agent-containing low melting point resin layer 103 laminated from at least the inside is prepared.

Subsequently, the laminated sheet 10 is molded by at least one of press molding, vacuum molding, pressure molding, and vacuum pressure molding (second step). In the second step, first, the laminated sheet 10 is placed in a molding device without forming ruled lines or the like on the portion that will become the flange portion 4 .
Subsequently, the laminated sheet 10 placed on the molding device is molded along the mold. At this time, the laminated sheet 10 may be heated. As a result, the paper tray container main body 1 having the bottom portion 2, the side wall portion 3, and the flange portion 4 corresponding to the shape of the mold is formed. The entire paper tray container body 1 does not have to follow the shape of the mold. For example, part of the side wall portion 3 and the flange portion 4 of the paper tray container body 1 may conform to the shape of the mold.

Next, the outer shape of the flange portion formed on the paper tray container main body 1 is removed from the other laminated sheet 10 portion to form an independent container (third step). In the third step, it may be cut with a Viku blade, a press die, or a rotary blade.

The operational effects of the paper tray container body 1 manufactured by the manufacturing method according to the present embodiment described above will be described using reference examples described below.

Here, in the paper tray container main body 1 manufactured by the manufacturing method according to the present embodiment, the paper base material laminated on the laminated sheet 20 has a basis weight of 50 g/m ² or more and 400 g/m ² or less, and the MD direction is A paper base material 102 having an elongation at break of 1.5% or more and less than 20% is used.
Therefore, the laminated sheet 20 can be molded by at least one of press molding, vacuum molding, pressure molding, and vacuum pressure molding.
In addition, in the paper tray container main body 1, the angle θ between the body portion 11 and the virtual plane VP extending in the directions X and Y at the tip 3a of the side wall portion 3 is 15° or more and 65° or less. And, the curvature radius R of the waist portion 12 is set to 8 mm or more and 30 mm or less. As a result, the ratio of the distance between the bottom portion 2 and the tip 3a of the side wall portion 3 along the direction Z to the maximum length of the opening end OE viewed from the direction Z is 2.0% without performing pulp molding. 25.0% or more, and a smooth flange portion 4 when viewed from the direction Z can be obtained. Therefore, according to this embodiment, it is possible to obtain the paper container 1 capable of exhibiting good airtightness and productivity.

The paper tray container main body according to one aspect of the present invention and the manufacturing method thereof are not limited to the above-described embodiment and modification.
For example, in the above embodiments and modifications, the barrier layer is provided on one main surface of the base material, but the present invention is not limited to this.
For example, barrier layers may be provided on both sides of the substrate. In this case, one barrier film layer and the other barrier film layer may have the same structure or different structures. In other words, one barrier layer and the other barrier layer may have the same function or different functions.

In the above-described embodiment and modified example, the paper tray container has a substantially rectangular shape when viewed from the vertical direction, but is not limited to this. When viewed from the vertical direction, the paper container may have a circular shape, an elliptical shape, or a polygonal shape.

The present invention will be described in more detail by the following examples, but the invention is not limited to these examples.

(Example 1)
A coextruded film of maleic anhydride-modified polyethylene/polyamide resin (6-nylon)/maleic anhydride-modified polyethylene was prepared as an inner barrier film layer with the layer structure shown in FIG. 4-1. The melting point Tm of this innermost layer was 70°C, and the extrusion resin temperature was 80°C.
Also, as a paper substrate, paper having a substantially rectangular shape and a basis weight of 150 g/m ² was prepared.
As the low melting point thermoplastic resin layer containing a foaming agent, 0.9 wt% of a foaming agent consisting of microshells having a film thickness of 2 to 15 µm and a spherical diameter of 5 to 50 µm is kneaded into an ethylene-vinyl acetate copolymer, and the resin is added. It was extruded to a thickness of 50 μm to form a low-melting thermoplastic resin layer containing a foaming agent.
The foaming starting temperature Th of the foaming agent is 95°C, which is 25°C higher than the melting point Tm of the innermost layer. The stable foaming temperature Te was 125° C., and the tray was heated and foamed at a higher temperature of 130° C. to give an expansion ratio of 9%.
As shown in FIG. 4-1, the laminated sheet has a barrier film layer/paper base layer/foaming agent-containing low-melting thermoplastic resin layer from the inner side of the container, as shown in FIGS. It was hot foamed and pressure molded into the paper tray shape shown.

(Example 2)
The low-melting-point thermoplastic resin layer containing the foaming agent was extruded to a thickness of 160 μm and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 1.

(Example 3)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 5.1 wt %, an extruded thickness of 160 μm, and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 1.

(Example 4)
The foaming agent-containing low-melting thermoplastic resin layer has a foaming agent compounding ratio of 5.1 wt%, a stable foaming temperature Te of 120°C, and a foaming start temperature Th of 90°C, which is 20°C higher than the melting point Tm of the innermost layer. bottom.
Others were the same as in Example 1.

(Example 5)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 1.

(Example 6)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 100° C., which was 30° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 1.

(Example 7)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 1.

(Example 8)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 87° C., which was 17° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 1.

(Example 9)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer. The stable foaming temperature Te was 130° C., and the tray was thermally foamed at a higher temperature of 140° C. to obtain an expansion ratio of 11%.
Others were the same as in Example 1.

(Example 10)
The melting point Tm of the innermost layer of the inner barrier film layer was 80°C, and the extrusion resin temperature was 90°C.
In the low melting point thermoplastic resin layer containing a foaming agent, the foaming starting temperature Th of the foaming agent is 100°C, which is 20°C higher than the melting point Tm of the innermost layer. The foaming ratio of molding was set to 8%.
Others were the same as in Example 1.

(Example 11)
A coextruded film of maleic anhydride-modified polyethylene/polyamide resin (6-nylon)/maleic anhydride-modified polyethylene was prepared as an inner barrier film layer with the layer structure shown in FIG. 4-2. The melting point Tm of this innermost layer was 70°C, and the extrusion resin temperature was 80°C.
Also, as a paper substrate, paper having a substantially rectangular shape and a basis weight of 150 g/m ² was prepared.
As the low melting point thermoplastic resin layer containing a foaming agent, 0.9 wt% of a foaming agent consisting of microshells having a film thickness of 2 to 15 µm and a spherical diameter of 5 to 50 µm is kneaded into an ethylene-vinyl acetate copolymer, and the resin is added. It was extruded to a thickness of 50 μm to form a low-melting thermoplastic resin layer containing a foaming agent.
The foaming starting temperature Th of the foaming agent is 95°C, which is 25°C higher than the melting point Tm of the innermost layer. The stable foaming temperature Te was 125° C., and the tray was heated and foamed at a higher temperature of 130° C. to give an expansion ratio of 9%.
As shown in Fig. 4-2, the laminated sheet has a barrier film layer, a paper base layer, a foaming agent-containing low-melting thermoplastic resin layer, and a paper base layer from the inside of the container. 1. The paper tray shape shown in FIG.

(Example 12)
The low-melting-point thermoplastic resin layer containing the foaming agent was extruded to a thickness of 160 μm and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 11.

(Example 13)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 5.1 wt %, an extruded thickness of 160 μm, and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 11.

(Example 14)
The foaming agent-containing low-melting thermoplastic resin layer has a foaming agent compounding ratio of 5.1 wt%, a stable foaming temperature Te of 120°C, and a foaming start temperature Th of 90°C, which is 20°C higher than the melting point Tm of the innermost layer. bottom.
Others were the same as in Example 11.

(Example 15)
The foaming agent-containing low melting point thermoplastic resin layer had an extruded thickness of 40 μm, a foaming agent compounding ratio of 1.5 wt %, and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 11.

(Example 16)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 100° C., which was 30° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 11.

(Example 17)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 11.

(Example 18)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 87° C., which was 17° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 11.

(Example 19)
The low-melting-point thermoplastic resin layer containing the foaming agent was thermoformed at a stable foaming temperature Te of 130° C. and the tray at a higher temperature of 140° C., resulting in an expansion ratio of 11%.
Others were the same as in Example 11.

(Example 20)
The melting point Tm of the innermost layer of the inner barrier film layer was 80°C, and the extrusion resin temperature was 90°C.
In the low melting point thermoplastic resin layer containing a foaming agent, the foaming starting temperature Th of the foaming agent is 100°C, which is 20°C higher than the melting point Tm of the innermost layer. The stable foaming temperature Te was 125° C., and the tray was heated and foamed at a higher temperature of 130° C. to give an expansion ratio of 8%.
Others were the same as in Example 11.

(Example 21)
A coextruded film of maleic anhydride-modified polyethylene/polyamide resin (6-nylon)/maleic anhydride-modified polyethylene was prepared as an inner barrier film layer with the layer structure shown in FIG. 4-3. The melting point Tm of this innermost layer was 70°C, and the extrusion resin temperature was 80°C.
Also, as a paper substrate, paper having a substantially rectangular shape and a basis weight of 150 g/m ² was prepared.
As the low melting point thermoplastic resin layer containing a foaming agent, 0.9 wt% of a foaming agent consisting of microshells having a film thickness of 2 to 15 µm and a spherical diameter of 5 to 50 µm is kneaded into an ethylene-vinyl acetate copolymer, and the resin is added. It was extruded to a thickness of 50 μm to form a low-melting thermoplastic resin layer containing a foaming agent.
The foaming start temperature Th of the foaming agent is 95°C, which is 25°C higher than the melting point Tm of the innermost layer. The stable foaming temperature Te was 125° C., and the tray was heat-molded at a higher temperature of 130° C. to give an expansion ratio of 9%.
As shown in FIG. 4-3, the laminate sheet has a barrier film layer/paper substrate layer/foaming agent-containing low-melting thermoplastic resin layer/paper substrate layer/foaming agent from the inside of the container. A thermoplastic resin layer having a low melting point was formed, and was subjected to thermal foaming pressure molding into a paper tray shape shown in FIGS. 1 and 2 .

(Example 22)
The low-melting-point thermoplastic resin layer containing the foaming agent was extruded to a thickness of 160 μm and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 21.

(Example 23)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 5.1 wt %, an extruded thickness of 160 μm, and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 21.

(Example 24)
The foaming agent-containing low-melting thermoplastic resin layer has a foaming agent compounding ratio of 5.1 wt%, a stable foaming temperature Te of 120°C, and a foaming start temperature Th of 90°C, which is 20°C higher than the melting point Tm of the innermost layer. bottom.
Others were the same as in Example 21.

(Example 25)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 21.

(Example 26)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 100° C., which was 30° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 21.

(Example 27)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 21.

(Example 28)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 87° C., which was 17° C. higher than the melting point Tm of the innermost layer.
Others were the same as in Example 21.

(Example 29)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming agent compounding ratio of 1.5 wt % and a foaming start temperature Th of 90° C., which was 20° C. higher than the melting point Tm of the innermost layer. The stable foaming temperature Te was 130° C., and the tray was thermally foamed at a higher temperature of 140° C. to obtain an expansion ratio of 11%.
Others were the same as in Example 21.

(Example 30)
The melting point Tm of the innermost layer of the inner barrier film layer was 80°C, and the extrusion resin temperature was 90°C.
In the low melting point thermoplastic resin layer containing a foaming agent, the foaming starting temperature Th of the foaming agent is 100°C, which is 20°C higher than the melting point Tm of the innermost layer. The foaming ratio of molding was set to 8%.
Others were the same as in Example 21.

(Comparative example 1)
A coextruded film of maleic anhydride-modified polyethylene/polyamide resin (6-nylon)/maleic anhydride-modified polyethylene was prepared as an inner barrier film layer with the layer structure shown in FIG. 4-1. The melting point Tm of this innermost layer was 70°C, and the extrusion resin temperature was 80°C.
Also, as a paper substrate, paper having a substantially rectangular shape and a basis weight of 150 g/m ² was prepared.
As the low-melting-point thermoplastic resin layer containing a blowing agent, 0.5 wt% of a blowing agent consisting of microshells having a film thickness of 2 to 15 μm and a spherical diameter of 5 to 50 μm is kneaded into an ethylene-vinyl acetate copolymer, and the resin is added. It was extruded to a thickness of 50 μm to form a low-melting thermoplastic resin layer containing a foaming agent.
The foaming starting temperature Th of the foaming agent is 90° C., which is 20° C. higher than the melting point Tm of the innermost layer. The stable foaming temperature Te was 125° C., and the tray was heat-molded at a higher temperature of 130° C. to give an expansion ratio of 6%.
As shown in FIG. 4-1, the laminated sheet has a barrier film layer/paper base layer/foaming agent-containing low-melting thermoplastic resin layer from the inner side of the container, as shown in FIGS. It was hot foamed and pressure molded into the paper tray shape shown.

(Comparative example 2)
The foaming agent-containing low-melting point thermoplastic resin layer contained 1.5 wt % of the foaming agent and had a thickness of 20 μm.
Others were the same as in Comparative Example 1.

(Comparative Example 3)
The foaming agent-containing low melting point thermoplastic resin layer contained 1.5 wt % of the foaming agent and had a thickness of 200 μm.
Others were the same as in Comparative Example 1.

(Comparative Example 4)
In the low-melting-point thermoplastic resin layer containing a foaming agent, the foaming starting temperature of the foaming agent to be kneaded was 80°C, which was 10°C higher than the melting point Tm of the innermost layer, and the compounding ratio of the foaming agent was 1.5 wt%.
Others were the same as in Comparative Example 1.

(Comparative Example 5)
The foaming agent-containing low-melting-point thermoplastic resin layer contained 1.5 wt % of the foaming agent.
The innermost barrier film layer had a melting point Tm of 70°C and an extrusion resin temperature of 70°C.
Others were the same as in Comparative Example 1.

(Comparative Example 6)
The foaming agent-containing low-melting point thermoplastic resin layer added 8 wt % of the foaming agent to be kneaded, and the foaming ratio was set to 6%.
Others were the same as in Comparative Example 1.

(Comparative Example 7)
The layer structure was the structure shown in FIG. 4-2, and the inner barrier film layer, paper base material, and foaming agent-containing low-melting thermoplastic resin layer were the same as those in Comparative Example 1, respectively.
Then, as shown in FIG. 4-2, each of the above layers is composed of a barrier film layer/a paper substrate layer/a foaming agent-containing low-melting thermoplastic resin layer/a paper substrate layer from the inner side of the container. . Other conditions were the same as in Comparative Example 1, and the paper tray container shape shown in FIGS.

(Comparative Example 8)
The foaming agent-containing low-melting point thermoplastic resin layer contained 1.5 wt % of the foaming agent and had a thickness of 20 μm.
Others were the same as in Comparative Example 7.

(Comparative Example 9)
The foaming agent-containing low melting point thermoplastic resin layer had a foaming start temperature of 90° C., a compounding ratio of 1.5 wt %, and a thickness of 200 μm.
Others were the same as in Comparative Example 7.

(Comparative Example 10)
In the low-melting-point thermoplastic resin layer containing a foaming agent, the foaming starting temperature of the foaming agent to be kneaded was 80°C, which was 10°C higher than the melting point Tm of the innermost layer, and the compounding ratio of the foaming agent was 1.5 wt%.
Others were the same as in Comparative Example 7.

(Comparative Example 11)
The foaming agent-containing low-melting-point thermoplastic resin layer contained 1.5 wt % of the foaming agent.
The innermost barrier film layer had a melting point Tm of 70°C and an extrusion resin temperature of 70°C.
Others were the same as in Comparative Example 7.

(Comparative Example 12)
The foaming agent-containing low melting point thermoplastic resin layer contains 8 wt% of the foaming agent to be kneaded, and the foaming ratio is 6.
%.
Others were the same as in Comparative Example 7.

(Comparative Example 13)
The layer structure was the structure shown in FIG. 4-3, and the inner barrier film layer, the paper substrate, and the foaming agent-containing low-melting thermoplastic resin layer were the same as in Comparative Example 1, respectively.
Then, as shown in FIG. 4-3, the above layers are arranged from the inner side of the container, barrier film layer / paper base layer / low melting point thermoplastic resin layer containing foaming agent / paper base layer / foamed A low melting point thermoplastic resin layer containing an agent was used. Others were the same as in Comparative Example 1, and hot pressure molding was carried out into the paper tray shape shown in FIGS. 1 and 2 .

(Comparative Example 14)
The foaming agent-containing low-melting point thermoplastic resin layer contained 1.5 wt % of the foaming agent and had a thickness of 20 μm.
Others were the same as in Comparative Example 13.

(Comparative Example 15)
The foaming agent-containing low melting point thermoplastic resin layer contained 1.5 wt % of the foaming agent and had a thickness of 200 μm.
Others were the same as in Comparative Example 13.

(Comparative Example 16)
In the low-melting-point thermoplastic resin layer containing a foaming agent, the foaming starting temperature of the foaming agent to be kneaded was 80°C, which was 10°C higher than the melting point Tm of the innermost layer, and the compounding ratio of the foaming agent was 1.5 wt%.
Others were the same as in Comparative Example 13.

(Comparative Example 17)
The foaming agent-containing low-melting-point thermoplastic resin layer contained 1.5 wt % of the foaming agent.
The innermost barrier film layer had a melting point Tm of 70°C and an extrusion resin temperature of 70°C.
Others were the same as in Comparative Example 13.

(Comparative Example 18)
The foaming agent-containing low-melting point thermoplastic resin layer added 8 wt % of the foaming agent to be kneaded, and the foaming ratio was set to 6%.
Others were the same as in Comparative Example 13.

(Comparative Example 19)
The layer structure was the structure shown in FIG. 4-4, and the inner barrier film layer 101 and the paper substrate 102 were the same as in Comparative Example 1, respectively.
Then, as shown in FIG. 4-4, each layer was a laminated sheet of barrier film layer/paper substrate layer from the inner side of the container, and no foam layer was formed. Others were the same as in Comparative Example 1, and hot pressure molding was carried out into the paper tray shape shown in FIGS. 1 and 2 .

<Evaluation method>
Thirty paper tray containers were prepared for each of the Examples and Comparative Examples, filled with 80 ml of water, and a cover film made by laminating polyethylene terephthalate with a thickness of 24 µm and linear low-density polyethylene with a thickness of 40 µm as a cover material. was fused to the flange of the paper tray container.
About 10 mm of the corner edge of the fused portion between the lid film and the flange was peeled off, and in this state, five pieces each were heated in a 600 W microwave oven for 2 minutes and 30 seconds.
Five out of 30 evaluators took out the heated paper tray container from the microwave oven and evaluated whether they could hold it in their hands.

<Microwave heating evaluation method>
Thirty evaluators held a microwave-heated paper tray container in their hands and asked whether they could safely hold it in their hands, and whether the container was deformed due to delamination, thickness change due to uneven foaming, and peeling between layers. It was evaluated whether or not it had occurred.
Regarding the above evaluation, ◯ indicates that 27 or more out of 30 evaluators evaluated as good, Δ indicates that 26 or more 24 or more evaluated as good, and 23 or less evaluates x.

<Paper tray container evaluation results>
In Examples 1-10, a few evaluators judged the heated container to be hot, but up to two evaluators judged it to be good.
Even in Examples 11 to 20, some evaluators judged that the heated container was hot, but up to two evaluators judged it to be good.
Even in Examples 21 to 30, some evaluators judged that the heated container was hot, but up to two evaluators judged it to be good.
Comparative Examples 1, 7 and 13 had a low foaming agent content of 0.5 wt % and an expansion ratio of 10%, but the amount of foaming was low and the heat insulation effect was low.
In Comparative Examples 2, 8, and 14, the thickness of the foaming agent-containing low-melting thermoplastic resin layer was as thin as 20 μm, and the heat insulation effect was small.
In Comparative Examples 3, 9, and 15, the thickness of the foaming agent-containing low melting point thermoplastic resin layer was increased to 200 μm, and the production cost was high, which did not meet the customer's wishes.
In Comparative Examples 4, 10, and 16, the foaming starting temperature of the foaming agent in the low-melting-point thermoplastic resin layer containing the foaming agent is as low as 80° C., and the foaming agent is 10° C. higher than the melting point. In addition to the problem that the paper and the foam layer have a low adhesion strength, there is a problem that the paper and the foam layer are easily peeled off.
In Comparative Examples 5, 11, and 17, the foaming start temperature of the foaming agent in the low melting point thermoplastic resin layer containing the foaming agent was set to 90°C, which is 20°C higher than the melting point, and the extrusion temperature was set to the same temperature as the melting point. I tried to prevent foaming during extrusion, but the extrusion temperature was too low, and there was a problem that stable extrusion could not be performed.
In Comparative Examples 6, 12, and 18, 8 wt % of the foaming agent to be kneaded was added to the foaming agent-containing low melting point thermoplastic resin layer, but the added amount was too large and the dispersion was poor. For this reason, stable foaming could not be performed, the layer thickness varied, and the flange could not be stably fused to the cover member.
Comparative Example 19 has a configuration in which no foaming agent is added to the low-melting thermoplastic resin layer, and when the contents are heated to a high temperature, the paper base layer alone has insufficient heat insulation, and the container can be opened at a high temperature. I had a problem that I couldn't hold it in my hand.
The above results are shown in Table 1.

Even if the paper tray container of the present invention was heated in a microwave oven, the following results were obtained as conditions for keeping the heated container from becoming hot.
The thickness of the low melting point thermoplastic resin layer containing a foaming agent is preferably 30 μm or more and 200 μm or less, more preferably 50 μm or more and 150 μm or less.
The foaming start temperature is preferably 10° C. higher than the extruded resin temperature.
Also, it was found that the compounding ratio of the foaming agent is preferably 0.9 wt % to 5.1 wt % of the low-melting thermoplastic resin.
Since the extrusion temperature of the low-melting thermoplastic resin layer containing the foaming agent>the foaming start temperature of the foaming agent>the extrusion temperature of the low-melting thermoplastic resin layer containing the foaming agent>the melting point of the low-melting thermoplastic resin, it can be sufficiently heated in a microwave oven. A paper tray container with good heat insulation that can be held by hand even when heated is obtained.
The paper tray container of the present invention is a container made of paper that can be easily incinerated. Not only can it be easily molded, but it can also be easily heated in the microwave. Moreover, as shown above, even if it is heated to a high temperature in a microwave oven, it can be held by hand and can be manufactured with a normal lamination machine, so that it is highly productive and can be manufactured at a low cost. The advantages of the present invention are great.

Reference Signs List 1: Shaping container 10: Laminated sheet 101: Barrier film layer 101b: Main surface (main surface of barrier film layer)
102: Paper base material layer 102b: main surface (main surface of paper base material)
103 ..... Foaming agent-containing thermoplastic resin layer 11 ..... Body portion 12 ..... Waist portion 2 ..... Bottom portion 3 ..... .. Side wall portion 3a .... Tip (tip of side wall portion)
4 Flange portion 4a Flange surface 5 Lid material 50 Packaging container OE・・・Open end L・・・・・・・・Maximum length (maximum length of open end)
VP: imaginary plane Q: angle R between the torso and the imaginary plane: radius of curvature of the waist H: Distance (Z-direction distance between the bottom and the tip of the side wall)

Claims (4)

Formed from a laminated sheet having, from the top, at least, a barrier film layer including a barrier layer, a paper base layer, and a low melting point thermoplastic resin layer containing a foaming agent,
The paper base layer has a basis weight in the range of 80 g/m ² or more and 400 g/m ² or less, and a breaking strength of 50 to 500 N/15 mm in the machine direction (MD direction) and in the vertical direction (TD direction). 30 to 400N/15mm,
The foaming agent-containing low melting point thermoplastic resin layer includes a thermoplastic polymer having a resin melting point of 130° C. or less, a foaming agent having a diameter of 5 to 50 μm, and a shell thickness of 2 to 15 μm. is a hydrocarbon, in the form of microcapsules,
1. A paper tray container comprising the laminated sheet as a base material, heat-molded, and foamed with the foaming agent to form a container having a flange. 2. The paper tray container according to claim 1, wherein the foaming agent-containing low melting point thermoplastic resin layer has an expansion ratio of 5 times or more, and a foaming start temperature of 16° C. or more higher than the melting point of the low melting point resin. 3. The paper tray container according to claim 1, wherein the foaming agent in the low melting point thermoplastic resin layer containing the foaming agent is 0.9 to 5.1% by weight with respect to the base resin. The paper tray container according to any one of claims 1 to 3, wherein the thickness of the low-melting thermoplastic resin layer containing a foaming agent is 30 to 200 µm.

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